Although previous research suggested that metformin may preserve left ventricular ejection fraction (LVEF) after STEMI, research presented March 31 at the American College of Cardiology (ACC) scientific session in Washington, D.C., found metformin did not improve LVEF in post-STEMI nondiabetic patients after they underwent PCI.

The Glycometabolic Intervention as Adjunct to Primary Percutaneous Coronary Intervention in ST-Segment Elevation Myocardial Infarction (GIPS) III trial evaluated the impact of metformin (Glucophage, Bristol-Myers Squibb) on LVEF after STEMI in patients without diabetes.

GIPS participants included 380 patients who underwent PCI after STEMI at the University Medical Center Groningen in the Netherlands. Participants received either 500 mg of metformin or placebo twice a day for four months.

The primary efficacy outcome was LVEF, which was assessed by MR imaging. A secondary efficacy measure was the incidence of adverse cardiac events (MACE), tracked for four months. Another secondary efficacy measure was N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration after four months.

At the four-month mark, all patients were still alive. LVEF was similar in both the metformin group and the placebo group (53.1 percent vs. 54.8 percent). Six patients in the metformin group experienced MACE (3.1 percent) compared with two in the placebo group (1.1 percent). NT-proBNP concentration was 167 ng/L in the metformin group (interquartile range [IQR] 65-393 ng/L) and 167 ng/L in the placebo group (IQR, 74-383 ng/L).

While the role of metformin in the prevention of heart failure after STEMI is not yet proven, the researchers are continuing to follow up to assess long-term clinical outcomes.

The results were simultaneously published in the Journal of the American Medical Association.